Fabric tester



Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE FABRIo'rEsT n 7 Harold A. 'Seylioth, Coronado, Calif. Application Mai-en's, 1948. serial No. 12,841 9 Claims. (91. 73-102) (Granted under the act of March 3, 1883, as I amended April 30, 1928; 370 0. G.; 757) This invention relates to a. fabric tester, and more particularly to a fabric tester for evaluating the strength and integrity of fabric covered aircraft surfaces.

Various devices have been developed in the past in an attempt to evaluate the condition of installed aircraft fabrics. None of these attempts has proved to be satisfactory. Furthermore, none of these devices provides direct, rapid and accurate evaluation of installed fabric surfaces except by methods involving extensive destructive tests and requiring experienced personnel.

Therefore, an object of this invention is to pro= vide a fabric tester which will permit direct, rapid, and accurate evaluation of the condition of in" stalled fabric surfaces.

Another object of this invention is to provide a fabric tester which imposes a minimum'of damage to the parts or surfaces under test.

Another object of this invention is to provide a fabric tester which will permit accurate evaluation of the condition of doped fabric surfaces, irrespective of the condition of the dope film.

Another object of this invention is to provide a fabric tester which does not require trained personnel for its operation, nor independent judgment on the part of personnel operating the tester.

A further object of this invention is to provide a fabric tester which is portable and inexpensive and can be used directlyon the fabric surface ofa plane.

A still further object of this invention is to provide a fabric tester which during use imposes damage to fabric so small in extent that it is pot-- sible to'repair the damage on the spot, while still conforming to aeronautical codes of safety.

Other objects and many of the attendant ad-- vantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description is in use, to abut at its leading edge l2, a sheet of taut fabric i3, stretched over the frame of an airplane, two ribs ll of which are shown.

. ,2 V A cylindrical plunger it, slidably mounted in the casing Iii, extends beyond the flange Ii and terminates in a fabric-penetrating, circular concave point 1-6. The length L of the point I6, from its apex H to its base i8, is preferably made greater than the diameter D at its base it. It

is further preferred to limit the length L to a flange ii is preferably value between D and 2D. The radius R of the concavity it of the point It is preferably greater than 1.25 times the diameter D and less than 6 times the diameter. The diameter D of the greater than two times-the diameter D and less than 4 times D.

Means is provided for biasing the point It outwardly of the casing. In this embodiment the means is a spring '2 i, positioned in the casing HI circumjacent the plunger l5 and compressed be tween a shoulder 22 on the plunger l5 and the cap 23 of the casing It. The shoulder 22, also limits outward movement of the point It.

The opposite end 24 of the plunger l5 extends through the casing cap 23 and terminates flush with the outer surface of the cap 23 when the tester is not being applied. This end 24 is scaled, in this embodiment, with colored bands 25, to indicate the degree of penetrating resistance of the fabric is to the point i6, as shown in Fig. 1. The outer band indicates fabric in a dangerous condition, while the inner bands indicate 'pro gre'ssively stronger conditions of the fabric.

Operation l the fabric,- with the axi of the tester being maintained perpendicular to the plane of the fabric, until the leading edge 12 of the flange H abuts the surface of the fabric it. as shown in 'Fig. 1. The tester is preferably given a slight twist to 1: break'a'ny loose threads of the fabric which may be binding the point or any frictional binding of the tester itself which may affect the reading.

The resistance pressure on the point tdexer-ted by the fabric compresses the spring 2 Lpermitting the end 2 3 of the plunger It to protrude beyond thecap '23 of the casing, therebygiving an instantaneous and direct reading of the fabric condition, as indicated by the color band which regis= ters with the outer surface'of the cap 23.

It has been found in operation that inexperi enced personnel can, by the use of the instant invention, quickly and accurately determine the strength of installed aircraft fabric, irrespective of the condition o'fthe dope film commonly coat- 3 ing such fabrics, and with a minimum of damage to such fabric surfaces.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described. I

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A fabric tester comprising a casing adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said casing and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, means biasing said point outwardly of said casing, and scale means to indicate th position of said plunger in said casing.

2. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, the length of said point being greater than the diameter thereof at its base, the concavity of said point being of radius greater than 1.25 times said base diameter and less than 6 times said diameter, means biasing said point outwardly of said casing, and scale means to indicate the position of said plunger in said casing.

3. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a, sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, the length of said point being greater than the di-'- ameter thereof at its base and less than twice said diameter, means biasing said point outwardly of said casing, and scale means to indicate the position of said plunger in said casing.

4. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, the length of said point being greater than the diameter thereof at its base, the diameter of said flange being greater than two times said point diameter and less than four times said point diameter, means biasing said point outwardly of said casing, and scale means to indicate the position of said plunger in said casing.

5. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, the

length of said point being greater than the diameter thereof at its base and less than twice said diameter, the concavity of said point being of radius greater than 1.25 times said base diameterand less than 6 times said diameter, the diameter of saidflangebeing greater than two times said point diameter and less than four times said point diameter, spring means biasing said point outwardly of said casing and compressible by said plunger to balance resistance pressure of the fabric against said point, and scale means to indicate the position of said plunger in said casing. 1 1

6. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-pentrating, circular concave point, said point being movable inwardly of said casing upon pressing of the tester against the fabric, the opposite end of said plunger, in normal inoperative condition, terminating flush with said casing and being scaled to indicate degree of penetrating resistance of the fabric, a spring in said casing,

circumjacent said plunger, biasing said point outwardly of said casing and compressible by said plunger to balance resistance pressure of the fabric against said point.

7. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly. of said casing upon pressing of the tester against the fabric, the length of said point being greater than the diameter thereof at its base, the opposite end of said plunger, in normal inoperative condition, terminating flush with said casing and being scaled to indicate degree of penetrating resistance of the fabric, and a spring in said casing, circumjacent said plunger, biasing said point outwardly of said casing and compressible by said plunger to balance resistance pressure of the fabric against said point,

8. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending beyond said flange and terminating in p a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon pressing Of the tester against the fabric, the length of said .point being greater than the diameter thereof at its base and less than twice said diameter, the diameter of said flange being greater than two times said point diameter and less than four times said point diameter, the opposite end of said plunger, in normal inoperative condition, terminating flush with said casing and being scaled to indicate degree of penetrating resistance of the fabric, and a spring in said casing, circumjacent said plunger, biasing said point outwardly of said casing and compressible by said plunger to balance resistance pressure of the fabric against said point.

9. A fabric tester comprising a casing having a circular flange on an end thereof adapted to abut a sheet of taut fabric, a cylindrical plunger slidably mounted in said casing, an end thereof extending, beyond said flange and terminating in a fabric-penetrating, circular concave point, said point being movable inwardly of said casing upon 5 6 pressing of the tester against the fabric, the REFERENCES CITED length of said point being greater than the The following references are of record in the ameter thereof at its base and less than twice said file of this patent. diameter, the concavity of said point being of radius greater than 1.25 times said base diameter 5 UNITED STATES PATENTS and less than 6 times said diameter, the diameter Number Name Date of said flange being greater than two times said 1,483,555 Ad Feb 12, 1924 point diameter and less than four times said point 1,519 02 Zimmerman t 1 1 1 2 diameter, the opposite end of said plunger, in 1,807,752 Poster June 2, 1931 normal inoperative condition, terminating flush 10 2,446,95 Ross Aug 10 1943 with said casing and being scaled to indicate degree of penetrating resistance of the fabric, and FOREIGN PATENTS a spring in said casing, circumj acent said plunger, Number Country Date biasing said point outwardly of said casing and 160,619 Great Britain Mar. 31, 921 compressible by said plunger to balance resistance 15 6 0,108 Germany May 20, 1936 pressure of the fabric against said point. 687,819 France May 5, 1930 HAROLD A. SEYBOTH. 

